When the total CK is reported at 480 IU/L, what does a CK-MB level of 8 µg/L indicate?

A total CK level of 480 IU/L indicates an elevation in creatine kinase (CK) levels, which can occur due to various muscular problems. The CK-MB fraction specifically represents heart muscle damage. A CK-MB level of 8 µg/L, when interpreted in the context of a total CK of 480 IU/L, suggests a relatively low proportion of CK-MB, particularly when compared to the total CK value.

In clinical practice, a high total CK with a low CK-MB suggests that the elevation is more likely due to conditions affecting skeletal muscle rather than the heart. Conditions such as strenuous exercise, skeletal muscle trauma, or other forms of muscle injury can elevate total CK levels without corresponding significant elevation in CK-MB. Therefore, the combination of a total CK of 480 IU/L and CK-MB of 8 µg/L suggests that the muscle injury is not predominantly from the heart, reducing suspicion for a heart attack or myocardial infarction.

The other options would imply a different underlying cause or significance in the context of the CK and CK-MB levels. While the total CK could indicate other muscular injuries, it is the relatively low CK-MB that guides the interpretation away from cardiac causes. Thus, this